When moving the seek bar around while in the progressive or streaming setting, it doesn't actually move to the indicated time on the bar. Rather, the video either jumps to a point ahead or a point behind. So trying to rewind a few seconds to see something I missed means I've got to rewatch the past minute or more.
I don't know if this is a limitation of the new video player or not, but it's a bit annoying.
Also, I'm running Firefox.